U.S. patent application number 09/966049 was filed with the patent office on 2002-04-04 for grid that tracks the occurrence of a n-dimensional matrix of combinatorial events in a simulation using a linear index.
Invention is credited to Boehm, Fritz A..
Application Number | 20020040285 09/966049 |
Document ID | / |
Family ID | 26973006 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020040285 |
Kind Code |
A1 |
Boehm, Fritz A. |
April 4, 2002 |
Grid that tracks the occurrence of a N-dimensional matrix of
combinatorial events in a simulation using a linear index
Abstract
A software monitor runs during the simulation of a digital
design to detect and report event combinations to a database for
test coverage analysis. The monitor is a grid that includes n
ordered axis declarations 72 that each correspond to a functional
attribute and list at least two valid functional states, logic
expressions 78 that test for the functional states and set axis
variables, and a grid declaration 80 that converts the axis
variables to a unique linear index value corresponding to the
cross-product of the achieved functional states and records hits.
The linear index is calculated by multiplying the integer value of
each axis variable (except the nth axis variable) by the product of
the sizes of each higher-order axis than the axis to which said
axis variable corresponds, summing the results, and adding the
integer value of the nth said axis variable.
Inventors: |
Boehm, Fritz A.; (Austin,
TX) |
Correspondence
Address: |
BOOTH & WRIGHT LLP
P O BOX 50010
AUSTIN
TX
78763-0010
US
|
Family ID: |
26973006 |
Appl. No.: |
09/966049 |
Filed: |
September 28, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09966049 |
Sep 28, 2001 |
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09406016 |
Sep 24, 1999 |
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60302593 |
Jul 2, 2001 |
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Current U.S.
Class: |
703/2 |
Current CPC
Class: |
G06F 17/10 20130101 |
Class at
Publication: |
703/2 |
International
Class: |
G06F 017/10 |
Claims
We claim the following invention:
1. A grid that monitors a design simulation to support design
verification coverage analysis, comprising: a monitor declaration
that provides a unique name for the grid; n ordered axis
declarations wherein n is at least 1, each said axis declaration
names an axis comprising a first axis through a nth axis, wherein
each said axis corresponds to a functional attribute of the design
and has an axis size that comprises two or more functional states
of said functional attribute and has a corresponding axis variable;
one or more logic expressions that evaluate whether the design has
achieved one or more of said functional states, said logic
expressions set each one of said n axis variables to an integer
value corresponding to said functional state when said logic
expressions evaluate true; and a grid declaration that converts
said n axis variables to a unique linear index value that
corresponds to the cross-product of said functional states achieved
by the design, said grid declaration also records a hit at said
unique linear index value.
2. A system that monitors a design simulation using a grid to
support design verification coverage analysis, comprising: a
monitor declaration that provides a unique name for the grid; n
ordered axis declarations wherein n is at least 1, each said axis
declaration names an axis comprising a first axis through a nth
axis, wherein each said axis corresponds to a functional attribute
of the design and has an axis size that comprises two or more
functional states of said functional attribute and has a
corresponding axis variable; one or more logic expressions that
evaluate whether the design has achieved one or more of said
functional states, said logic expressions set each one of said n
axis variables to an integer value corresponding to said functional
state when said logic expressions evaluate true; and a grid
declaration that converts said n axis variables to a unique linear
index value that corresponds to the cross-product of said
functional states achieved by the design, said grid declaration
also records a hit at said unique linear index value.
3. A method that makes a grid that monitors a design simulation to
support design verification coverage analysis, comprising:
providing a monitor declaration that provides a unique name for the
grid; providing n ordered axis declarations wherein n is at least
1, each said axis declaration names an axis comprising a first axis
through a nth axis, wherein each said axis corresponds to a
functional attribute of the design and has an axis size that
comprises two or more functional states of said functional
attribute and has a corresponding axis variable; providing one or
more logic expressions that evaluate whether the design has
achieved one or more of said functional states, said logic
expressions set each one of said n axis variables to an integer
value corresponding to said functional state when said logic
expressions evaluate true; and providing a grid declaration that
converts said n axis variables to a unique linear index value that
corresponds to the cross-product of said functional states achieved
by the design, said grid declaration also records a hit at said
unique linear index value.
4. A method that monitors a design simulation using a grid to
support design verification coverage analysis, comprising:
declaring a monitor in a monitor declaration that provides a unique
name for the grid; declaring n ordered axes using axis
declarations, wherein n is at least 1, each said axis declaration
names an axis comprising a first axis through a nth axis, wherein
each said axis corresponds to a functional attribute of the design
and has an axis size that comprises two or more functional states
of said functional attribute and has a corresponding axis variable;
evaluating one or more logic expressions to determine whether the
design has achieved one or more of said functional states; setting
each one of said n axis variables to an integer value corresponding
to said functional state when said logic expressions evaluate true;
and using a grid declaration to convert said n axis variables to a
unique linear index value that corresponds to the cross-product of
said functional states achieved by the design and to record a hit
at said unique linear index value.
5. A program storage device readable by a machine, tangibly
embodying a program of instructions executable by the machine to
perform a method that monitors a design simulation using a grid to
support design verification coverage analysis, comprising:
declaring a monitor in a monitor declaration that provides a unique
name for the grid; declaring n ordered axes using axis
declarations, wherein n is at least 1, each said axis declaration
names an axis comprising a first axis through a nth axis, wherein
each said axis corresponds to a functional attribute of the design
and has an axis size that comprises two or more functional states
of said functional attribute and has a corresponding axis variable;
evaluating one or more logic expressions to determine whether the
design has achieved one or more of said functional states; setting
each one of said n axis variables to an integer value corresponding
to said functional state when said logic expressions evaluate true;
and using a grid declaration to convert said n axis variables to a
unique linear index value that corresponds to the cross-product of
said functional states achieved by the design and to record a hit
at said unique linear index value.
6. A dependent claim according to claim 1, 2, 3, 4 or 5 wherein
said grid declaration maintains a map of hits at each linear index
value determined during a simulation, and downloads said map to a
database.
7. A dependent claim according to claim 1, 2, 3, 4 or 5 wherein
said unique linear index value is determined by multiplying the
integer value of each said axis variable except the nth said axis
variable by the product of the sizes of each higher-order axis than
the axis to which said axis variable corresponds, summing the
results, and adding the integer value of the nth said axis
variable.
8. A dependent claim according to claim 1, 2, 3, 4 or 5, wherein
said monitor declaration, said axis declarations, said logic
expressions, and said grid declaration are translated into a
computer program comprising a higher-order software language using
a parser.
9. A dependent claim according to claim 8 wherein said parser
further translates each said unique linear index value to a
character string comprising a concatenation of character strings
that correlate to said grid name and to each said functional state
within said cross-product achieved by the design.
10. A grid that monitors a design simulation to support design
verification coverage analysis, comprising: a monitor declaration
that provides a unique name for the grid; n ordered axis
declarations wherein n is at least 1, each said axis declaration
names an axis comprising a first axis through a nth axis, wherein
each said axis corresponds to a functional attribute of the design
and has an axis size that comprises two or more functional states
of said functional attribute and has a corresponding axis variable;
one or more logic expressions that evaluate whether the design has
achieved one or more of said functional states, said logic
expressions set each one of said n axis variables to an integer
value corresponding to said functional state when said logic
expressions evaluate true; a grid declaration that converts said n
axis variables to a unique linear index value that corresponds to
the cross-product of said functional states achieved by the design
by multiplying the integer value of each said axis variable except
the nth said axis variable by the product of the sizes of each
higher-order axis than the axis to which said axis variable
corresponds, summing the results, and adding the integer value of
the nth said axis variable, said grid declaration also records a
hit and maintains a map of hits at each linear index value
determined during a simulation, and downloads said map to a
database; and a parser that translates said monitor declaration,
said axis declarations, said logic expressions, and said grid
declaration into a computer program comprising a higher-order
software language, said parser further translates each said unique
linear index value to a character string comprising a concatenation
of character strings that correlate to said grid name and to each
said functional state within said cross-product achieved by the
design.
11. A system that monitors a design simulation using a grid to
support design verification coverage analysis, comprising: a
monitor declaration that provides a unique name for the grid; n
ordered axis declarations wherein n is at least 1, each said axis
declaration names an axis comprising a first axis through a nth
axis, wherein each said axis corresponds to a functional attribute
of the design and has an axis size that comprises two or more
functional states of said functional attribute and has a
corresponding axis variable; one or more logic expressions that
evaluate whether the design has achieved one or more of said
functional states, said logic expressions set each one of said n
axis variables to an integer value corresponding to said functional
state when said logic expressions evaluate true; a grid declaration
that converts said n axis variables to a unique linear index value
that corresponds to the cross-product of said functional states
achieved by the design by multiplying the integer value of each
said axis variable except the nth said axis variable by the product
of the sizes of each higher-order axis than the axis to which said
axis variable corresponds, summing the results, and adding the
integer value of the nth said axis variable, said grid declaration
also records a hit and maintains a map of hits at each linear index
value determined during a simulation, and downloads said map to a
database; and a parser that translates said monitor declaration,
said axis declarations, said logic expressions, and said grid
declaration into a computer program comprising a higher-order
software language, said parser further translates each said unique
linear index value to a character string comprising a concatenation
of character strings that correlate to said grid name and to each
said functional state within said cross-product achieved by the
design.
12. A method that makes a grid that monitors a design simulation to
support design verification coverage analysis, comprising:
providing a monitor declaration that provides a unique name for the
grid; providing n ordered axis declarations wherein n is at least
1, each said axis declaration names an axis comprising a first axis
through a nth axis, wherein each said axis corresponds to a
functional attribute of the design and has an axis size that
comprises two or more functional states of said functional
attribute and has a corresponding axis variable; providing one or
more logic expressions that evaluate whether the design has
achieved one or more of said functional states, said logic
expressions set each one of said n axis variables to an integer
value corresponding to said functional state when said logic
expressions evaluate true; providing a grid declaration that
converts said n axis variables to a unique linear index value that
corresponds to the cross-product of said functional states achieved
by the design by multiplying the integer value of each said axis
variable except the nth said axis variable by the product of the
sizes of each higher-order axis than the axis to which said axis
variable corresponds, summing the results, and adding the integer
value of the nth said axis variable, said grid declaration also
records a hit and maintains a map of hits at each linear index
value determined during a simulation, and downloads said map to a
database; and providing a parser that translates said monitor
declaration, said axis declarations, said logic expressions, and
said grid declaration into a computer program comprising a
higher-order software language, said parser further translates each
said unique linear index value to a character string comprising a
concatenation of character strings that correlate to said grid name
and to each said functional state within said cross-product
achieved by the design.
13. A method that monitors a design simulation using a grid to
support design verification coverage analysis, comprising:
declaring a monitor in a monitor declaration that provides a unique
name for the grid; declaring n ordered axes using axis
declarations, wherein n is at least 1, each said axis declaration
names an axis comprising a first axis through a nth axis, wherein
each said axis corresponds to a functional attribute of the design
and has an axis size that comprises two or more functional states
of said functional attribute and has a corresponding axis variable;
evaluating one or more logic expressions to determine whether the
design has achieved one or more of said functional states; setting
each one of said n axis variables to an integer value corresponding
to said functional state when said logic expressions evaluate true;
using a grid declaration that converts said n axis variables to a
unique linear index value that corresponds to the cross-product of
said functional states achieved by the design by multiplying the
integer value of each said axis variable except the nth said axis
variable by the product of the sizes of each higher-order axis than
the axis to which said axis variable corresponds, summing the
results, and adding the integer value of the nth said axis
variable, said grid declaration also records a hit and maintains a
map of hits at each linear index value determined during a
simulation, and downloads said map to a database; and translating
said monitor declaration, said axis declarations, said logic
expressions, and said grid declaration into a computer program
comprising a higher-order software language, and translating each
said unique linear index value to a character string comprising a
concatenation of character strings that correlate to said grid name
and to each said functional state within said cross-product
achieved by the design.
14. A program storage device readable by a machine, tangibly
embodying a program of instructions executable by the machine to
perform a method that monitors a design simulation using a grid to
support design verification coverage analysis, comprising:
declaring a monitor in a monitor declaration that provides a unique
name for the grid; declaring n ordered axes using axis
declarations, wherein n is at least 1, each said axis declaration
names an axis comprising a first axis through a nth axis, wherein
each said axis corresponds to a functional attribute of the design
and has an axis size that comprises two or more functional states
of said functional attribute and has a corresponding axis variable;
evaluating one or more logic expressions to determine whether the
design has achieved one or more of said functional states; setting
each one of said n axis variables to an integer value corresponding
to said functional state when said logic expressions evaluate true;
using a grid declaration that converts said n axis variables to a
unique linear index value that corresponds to the cross-product of
said functional states achieved by the design by multiplying the
integer value of each said axis variable except the nth said axis
variable by the product of the sizes of each higher-order axis than
the axis to which said axis variable corresponds, summing the
results, and adding the integer value of the nth said axis
variable, said grid declaration also records a hit and maintains a
map of hits at each linear index value determined during a
simulation, and downloads said map to a database; and translating
said monitor declaration, said axis declarations, said logic
expressions, and said grid declaration into a computer program
comprising a higher-order software language, and translating each
said unique linear index value to a character string comprising a
concatenation of character strings that correlate to said grid name
and to each said functional state within said cross-product
achieved by the design.
Description
[0001] This application claims the benefits of the earlier filed
U.S. Provisional application Ser. No. 60/302,593, filed Jul. 2,
2001 (02.07.2001), which is incorporated by reference for all
purposes into this specification.
[0002] Additionally, this application is a continuation-in-part of
U.S. patent application Ser. No. 09/406,016, filed Sep. 24, 1999
(24.09.1999), entitled "Method and Apparatus that Reports Multiple
Status Events with a Single Monitor", which is incorporated by
reference for all purposes into this specification and referred to
herein as "the Grid Patent."
CROSS REFERENCE TO RELATED APPLICATIONS
[0003] This application is related to U.S. patent application Ser.
No. 09/406,017, filed Sep. 24, 1999 (24.09.1999), entitled "Method
and Apparatus for a Monitor that Detects and Reports a Status Event
to a Database", which is incorporated by reference for all purposes
into this specification and referred to herein as "the Monitor
Patent."
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] The present invention relates to design verification in the
digital computing field. More particularly, the present invention
relates to a coverage analysis tool and method that monitors a
simulation test on a digital design to detect and report
interesting events and states achieved during the simulation.
[0006] 2. Description of the Related Art
[0007] A digital design performs a finite number of logical
functions or operations. For instance, a typical digital design
such as a microprocessor might support four separate operations
called addition (a), multiplication (m), subtraction (s), and
division (d). Within each operation, different specific events may
occur. For instance, addition of two negative numbers may occur, or
addition of two positive numbers may occur.
[0008] A digital design will support many combinations of events
where each type of specific event is called a state. In more
complex designs, events may happen serially so that the number of
states is increased. For instance, the operation sequence
addition-multiplication-division (amd) is a different state than
the operation sequence addition-multiplication-- subtraction (ams).
More states exist in the digital design when each a, m, s, and d
operation supports various types of operands (i.e., positive,
negative, and zero). Each permutation combining possible specific
events results in a different state.
[0009] Exhaustive verification of modern digital designs such as
microprocessors is virtually impossible because such designs may
attain an almost incalculable number of states. A designer must
therefore determine a sub-list of states that represent the most
interesting states. The sub-list of states should include
functional events, which are events that can be defined based on
the specification of the design, and implementation events, which
are specific to how the designer chose to implement the
specification. While the sub-list of interesting states is not
exhaustive, it usually provides a yardstick for measuring test
coverage. To gain an adequate level of confidence that the design
is functioning correctly, it is necessary to verify whether the
design attains all of these interesting states during operation or
simulation.
[0010] Verification of digital designs is usually done using a
simulator. A simulator is a program that runs the design file of a
digital design in order to recreate how the design would perform on
a computer chip. A common method for generating test stimulus is to
use a random, or directed random, test case generator. With random
test case generation, the correctness of the design being simulated
is established by having the results predicted automatically by
some sort of reference model. The actual checking may take many
forms, ranging from comparing the final results in memory to
checking internal state cycle-by-cycle. There are major advantages
to using random test case generation. Computer programs can
generate test cases much faster than people can, so many more
design states can be reached in the same amount of time using
random test case generation. This is critically important for
complex designs which need a reasonable time-to-market. Also, by
introducing randomness, the verification engineer can think of a
general set of tests that would hit interesting states, and let the
computer generate all the special cases. In many cases, the random
test generator ends up creating situations that a tester may not
have thought to create.
[0011] One drawback to random test case generation is that it is
difficult to know exactly what is being tested. Consequently, it is
difficult to gain an adequate level of confidence that the design
is attaining all of the required states determined by the designer
to be interesting. A number of approaches have been used to
determine when a design has been sufficiently verified using random
test case generation. One method is to use statistical data from
previous designs to predict the expected bug rate. This requires
that the statistical data exist for the same style of design and
the same test generation tool. Another method is to simply try as
many different test strategies with the random test generator as
one can think of, and then run them until the bug rate decreases. A
third method is to use coverage analysis tools to quantify the
percentage of the existing design states that have been hit.
[0012] Existing coverage analysis tools typically traverse the
source code of the design to generate a list of unique states to be
tracked. Since the resulting coverage data is based purely on the
existing source code, the coverage data is very specific to the
implementation of the design. There is no way to use the coverage
data to evaluate functional coverage, or how much of the
specification that details the functional requirements of the
design has been tested. It can also be difficult to evaluate how
many of the cases that have not been hit are actually interesting.
And finally, current source-code generated coverage tools do not
generate and track interesting combinations of states, so
source-code generated data does not include data on interesting
combinations of events.
[0013] The present invention introduces a method for evaluating
coverage from either a functional or an implementation perspective,
including combinatorial coverage. It provides an easy way to write
a software monitor to identify an event or state in a design
simulation and then log the information concerning attainment of
the state into a database for further analysis. Designers can then
analyze the database to determine if the simulation provides
adequate coverage of a particular list of interesting events. If
the simulation does not adequately cover certain events, the cause
can then be investigated. The list of events monitored and reported
into the database can be driven by the sub-list of events
determined by the designer to be interesting.
[0014] One way that designers identify interesting combinatorial
events is to take the cross product of two or more events. For
example, designers typically want to verify design functionality
for every possible combination of two back-to-back instructions.
Likewise, designers will likely want to test all possible
combinations of operands for an instruction. As designs become more
complex and capable of executing more unique instructions with more
types of operands, more interesting states can be expressed as a
cross product of different events.
[0015] The assignee of the present invention, Intrinsity, Inc., has
developed and patented a new logic design style called N-NARY
Dynamic Logic ("NDL"). A new logic design style requires new coding
techniques to verify the computer-aided design of the logic
circuits and their constituent subcircuits, and NDL is no
exception. NDL is a dynamic logic design style fully described in
U.S. Pat. No. 6,069,49, titled "Method and Apparatus for a N-NARY
Logic Circuit Using 1-of-N Signals", which is incorporated by
reference for all purposes and is referred to herein as "The N-NARY
Patent." NDL uses a multiphase clock scheme that self-synchronizes
the logic flow, thus eliminating the need for static latches and
registers and elaborate timing schemes. NDL synchronization is
further described in detail in U.S. Pat. No. 6,118,304, entitled
"Method and Apparatus for Logic Synchronization," which is
incorporated for all purposes and referred to herein as "the Logic
Synchronization Patent."
[0016] The simulation of NDL is fully described in the following
copending patent applications: U.S. patent application Ser. No.
09/405,618, filed Sep. 24, 1999 (24.09.1999), titled "Software
Modeling of Logic Signals Capable of Holding More Than Two Values",
and U.S. patent application Ser. No. 09/405,474, filed Sep. 14,
1999 (24.09.1999), titled "Four-State Simulation for Non-Binary
Logic", both of which are incorporated by reference for all
purposes.
[0017] As described in further detail in the N-NARY patent, the
N-NARY logic family supports a variety of signal encodings,
including 1-of-4. In 1-of-4 encoding, four wires are used to
indicate one of four possible values. In contrast, traditional
static logic design uses two wires to indicate four values, as is
demonstrated in Table 1. In Table 1, the A.sub.0 and A.sub.1 wires
are used to indicate the four possible values for operand A: 00,
10, 10, and 11. Table 1 also shows the decimal value of an encoded
1-of-4 signal corresponding to the two-bit operand value, and the
methodology by which the value is encoded using four wires.
1TABLE 1 N-NARY (1-of-4) Signal A Decimal N-NARY (1-of-4) Signal A
2-bit operand value Value 1-of-4 wires asserted A.sub.1 A.sub.0 A
A[3] A[2] A[1] A[0] 0 0 0 0 0 0 1 0 1 1 0 0 1 0 1 0 2 0 1 0 0 1 1 3
1 0 0 0
[0018] While "traditional" dual-rail dynamic logic also uses four
wires to represent two bits, the dual-rail scheme always requires
two wires to be asserted, whereas NDL only requires assertion of
one wire, thus reducing power and signal noise. Other benefits of
NDL over dual-rail dynamic logic are described in the N-NARY
Patent. All signals in NDL, including 1-of-4, are of the 1-of-N
form where N is any integer greater than one. More than one wire
will never be asserted for a valid 1-of-N signal. Similarly, NDL
requires that a high voltage be asserted on only one wire for all
values, even the value for zero (0).
[0019] Any one NDL gate may comprise multiple inputs and/or
outputs. In such a case, a variety of different N-NARY encodings
may be employed. For instance, consider a gate that comprises two
inputs and two outputs, where the inputs are a 1-of-4 signal and a
1-of-2 signal and the outputs comprise a 1-of-4 signal and a 1-of-3
signal. Variables such as P, Q, R, and S may be used to describe
the encoding for these inputs and outputs. One may say that one
input comprises 1-of-P encoding and the other comprises 1-of-Q
encoding, wherein P equals two and Q equals four. Similarly, the
variables R and S may be used to describe the outputs. One might
say that one output comprises 1-of-R encoding and the other output
comprises 1-of-S encoding, wherein R equals four and S equals 3.
Through the use of these, and other, additional variables, it is
possible to describe multiple 1-of-N signals used in NDL gates that
comprise a variety of different encodings.
[0020] 1-of-N signals used in NDL gates are named according to a
signal naming convention that is fully described in a copending
patent application, U.S. patent application Ser. No.09/210,408,
titled "Method and Apparatus for N-NARY Hardware Description
Language", which is incorporated by reference for all purposes and
is referred to herein as "The Hardware Description Patent." The
signal naming convention identifies certain information that
characterizes the signal, specifically information concerning
1-of-N degree, evaluation, and clock phase. For further details
regarding the meaning and interpretation of the various fields in a
signal name, the reader is encouraged to refer to the Hardware
Description Patent. A typical name for a typical 1-of-N signal
might be "disp_valid.sub.--4H2", which indicates a 1-of-4 signal
described as "disp_valid" that evaluates on the rising edge of the
second clock phase. The present invention refers to signals using
the signal naming convention as described in the Hardware
Description Patent.
SUMMARY OF THE INVENTION
[0021] The present invention comprises a method and apparatus that
monitors the simulation of a digital design such as a processor,
and detects and reports certain events and combinations of events
to a database. Conceptually, the monitor first constructs an
n-dimensional array wherein each array entry corresponds to a
processor state comprising the cross product of multiple specific
verification events determined by the designer to be a combination
of events of interest. The monitor then monitors the simulation,
and counts the number of times each state corresponding to each
array entry is encountered. The monitor, also referred to as a grid
in this description, runs in parallel with the simulation, and if
the grid detects a specified event that is an entry in the
n-dimensional array, it logs the information and reports the
information to a database.
[0022] The grid includes a monitor declaration that provides a
unique name for the grid, n ordered axis declarations, wherein n is
at least 1, that name a first through a nth axis, one or more logic
expressions, and a grid declaration. Each axis declaration
corresponds to a functional attribute of the design and lists two
or more functional states of the functional attribute. The size of
each axis comprises the number of functional states listed in its
axis declaration. The logic expressions evaluate whether the design
has achieved one of the functional states along each axis, and if a
logic expression relating to an axis evaluates true, it sets the
axis variable for that axis to the integer value corresponding to
the functional state found. If all n axis variables are set to
valid values during the evaluation of the logic expressions, the
grid declaration converts the n axis variables to a unique linear
index value that corresponds to the cross-product of the functional
states achieved by the design, and records hits at each unique
linear index value determined. The grid declaration can maintain a
hit map indexed to the unique linear index for later downloading to
a database.
[0023] The grid calculates the unique linear index value by
multiplying the integer value of each axis variable (except the nth
axis variable) by the product of the sizes of each higher-order
axis than the axis to which said axis variable corresponds, summing
the results, and adding the integer value of the nth said axis
variable.
[0024] The grid also includes a parser that translates the grid
into a computer program comprising a standard higher-order software
language such as C++. In some embodiments, the parser further
translates each unique linear index value to a character string
comprising a concatenation of character strings that correlate to
the monitor name and to each functional state within the
cross-product of functional states achieved by the design. The hit
map can be reported to the database in either the linear index
format or the character string format. The present invention
further comprises embodiments where a grid uses either a fully
populated state array, wherein all permutations of valid states for
each axis are included, or a sparsely populated state array,
wherein only permutations of the valid states of each axis that are
of interest to the designer are included.
DESCRIPTION OF THE DRAWINGS
[0025] To further aid in understanding the invention, the attached
drawings help illustrate specific features of the invention and the
following is a brief description of the attached drawings:
[0026] FIG. 1 is a system level description of the present
invention.
[0027] FIG. 2 illustrates the general organization of an example
monitor.
[0028] FIG. 3 is a diagram illustrating a cross product of events
for a grid comprising a fully populated state array.
[0029] FIG. 4 illustrates the general organization of the present
invention.
[0030] FIG. 5 shows the relative positions of each of the n columns
used to transform a list of n variables having integer values to
the linear index of the present invention.
[0031] FIG. 6A shows the 3-column conversion numbering system the
present invention creates for a 4.times.3.times.3 grid.
[0032] FIG. 6B shows the conversion of an example integer variable
list 2, 0, 1 to its linear index value 19 for a 4.times.3.times.3
grid, according to one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The present invention is a method and apparatus that
monitors the simulation of a digital design such as a processor,
and detects and reports certain events and combinations of events
to a database. This disclosure describes numerous specific details
that include specific software structures and example instruction
streams in order to provide a thorough understanding of the present
invention. One skilled in the art will appreciate that one may
practice the present invention without these specific details.
[0034] In the embodiment described herein, the present invention is
implemented in a monitor language described in detail in the
Monitor and Grid Patents. That description is not repeated here,
and readers interested in the particulars of the monitor language
are encouraged to refer to the Monitor and Grid Patents for the
specific information they seek. As described in the Monitor and
Grid Patents, the monitor language provides a straightforward
method for a user to create a software monitor that is easily
converted by a parser into a standard higher-order software
language such as the C++ language. C++ is a compiled language, that
is, C++ programs are written in a human-readable script and this
script is then provided to another program called a compiler, which
generates a machine-readable numeric code that can be loaded into,
and directly executed by, a computer. Those skilled in the art are
very familiar with C++, and many articles and texts are available
which describe the language in detail. The exemplary embodiment
detailed herein is described using a monitor language that uses
existing C++ constructs as an initial foundation, and adds a set of
statements using keywords that are translated by a parser into
multiple C++ routines and functions, which are then compiled for
execution by the simulator. However, those skilled in the art will
understand that monitors and grids can be developed in other
higher-order object-oriented programming languages (such as Java)
or modified versions of those languages, without departing from the
present invention. Similarly, those skilled in the art will
understand that the parser of the present invention can be modified
to translate a monitor or grid written in the monitor language
described in the Monitor and Grid Patents into a programming or
computer language other than C++, without departing from the
present invention.
[0035] As described in more detail in the Monitor and Grid Patents,
monitors and grids are used to evaluate the completeness of the
simulation of a digital design such as a processor. More
specifically, a monitor checks a design under simulation for
specific verification events. If the monitor detects a specific
event, it reports the information to a database. As described in
the Grid Patent, a grid is a monitor that detects a cross product
of verification events and reports each cross product as a single
status event to a database. Both patents describe the monitor
language used to create software monitors and grids that may be
translated into a standard computer language by a parser.
[0036] FIG. 1 illustrates the present invention at a system level.
A user at a workstation 10 runs a simulation. A workstation 10 is
coupled to a server 12, which is in turn coupled to a shared
storage device 14. A server 12 provides the facilities with which
to run the simulation. When the simulation is run, one or more
monitors and/or grids 20 run together with the simulator 18 and
check the design 16 for a particular specified state. An individual
monitor 20 detects and reports a status event to a database 22. An
individual grid 20 detects a cross product of verification events
and reports each cross product as a single status event to the
database 22.
Monitors
[0037] FIG. 2 and Table 2 illustrate an example monitor that is
described in more detail in the Monitor Patent. The monitor
comprises a monitor declaration 50, zero or more signal
declarations 52, zero or more bus declarations 54, and one or more
logic expressions 56.
2TABLE 2 monitor (ADD) { // monitor declaration signal *val =
"disp_valid_2h1"; // signal declaration bus op =
"disp_opcode_B[5:0,2]_4h1"; // bus declaration if ((*val == V1)
&& (bus_val(op) == 0.times.18)) return true; // logic
expression } // end of monitor
[0038] As described in the Monitor Patent, the monitor declaration
defines the unique name of the monitor; the signal declaration
defines a variable name local to the monitor which is a pointer to
a signal in the design; the bus declaration defines the name of a
bus, which is a set of signals used to represent a single value;
and the logic expression specifies the event that the monitor is
evaluating using the signal and bus values as operands in an
expression that uses logical operators and can be evaluated as true
or false. When the event specified by the logic expression has
occurred and the logic expression evaluates true, the monitor
returns a true value.
[0039] To use the monitor in a simulation, the monitor code is
translated by a parser into a software routine such as a C++
function. The software routine is then compiled and dynamically or
statically linked into the simulation environment, which includes
software that evaluates each monitor during every simulation cycle
and tracks how many times each monitor evaluates to true during a
simulation. At the end of the simulation, the simulation
environment summarizes this coverage information and logs it in a
database for future analysis. This approach to writing and using
monitors provides an easy way to define functional verification
events or design state events, provides an automated method to
compile and link the code into the simulation, and provides an
automated method to report the coverage results to a database.
Grids
[0040] The monitor described above provides an easy way to track
the occurrence of individual states or events within a simulation.
Moreover, at any given time during a single simulation, multiple
monitors can be running to track multiple events. A designer
interested in ascertaining whether a certain interesting
combination of events has occurred during a simulation could create
the monitors to detect each event, and then analyze the database to
determine whether each of the relevant monitors recorded a hit
during the proper time frame.
[0041] However, a more efficient way to detect and record the
occurrence of interesting combinations of events is to create a
single grid that covers all of the events, rather than multiple
monitors that each cover one of the events. A grid is essentially a
monitor that is capable of detecting combinations of interesting
events and reporting a single hit to the database that corresponds
to the event combination. Combinations of events in the test
coverage of a digital design can be described as a "cross product"
of some number of events. For example, one may want to test a
digital design such as a processor for all combinations of two
instructions running back-to-back. Likewise, designers may want to
test all possible combinations of external bus accesses. FIG. 3 is
a diagram illustrating an array of interesting test events wherein
each cell is an event represented by a different cross product of
the possible functional states (1, 2, and 3) of two different
functional attributes (a and b) under test.
[0042] Examples of functional attributes that might be tested
include op codes (functional instructions like add, subtract, or
multiply and the like, or a register instruction like load, store,
and the like), cache states (e.g., a dirty miss, a clean miss, a
clean hit, a dirty hit, or a non-cacheable state), bus access
states (e.g., a simple request, a snoop, an invalidate, an
emulation access, and block reads and writes); access sizes (e.g.,
1Kbyte accesses, 2Kbyte accesses, 4Kbyte accesses, etc. ) and
address states (e.g., boundary crossings or unaligned addresses).
Each functional attribute has two or more possible functional
states.
[0043] Returning to FIG. 3, a designer might wish to test for the
combination of an add instruction followed by a subtract
instruction wherein each instruction has an operand that is either
positive, zero, or negative. In this example, attribute a might be
the add instruction having functional states positive operand (1),
zero (2), and negative operand (3). Similarly, attribute b might be
the subtract instruction having functional states positive operand
(1), zero (2), and negative operand (3). FIG. 3 shows the fully
populated cross product of events wherein a1b1 represents the state
where the instructions are run back-to-back and both have a
positive operand; a1b2 represents the state where the instructions
are run back-to-back and the add instruction has a positive operand
while the subtract instruction includes a zero; a1b3 represents the
state where the instructions are run back-to-back and the add
instruction has a positive operand while the subtract instruction
has a negative operand, and so forth. Note that all cells of FIG. 3
are occupied, indicating a fully populated state array or cross
product of events. The Grid Patent describes how grids can be
written that result in a sparsely populated state array or cross
product of events, which might be more appropriate in certain
situations (e.g., when testing two or more functional attributes
wherein each has valid states that either cannot be validly
combined or result in uninteresting combinations.) The present
invention functions using either a fully populated state array or a
sparsely populated state array. For clarity, the following
description and examples assume a fully populated state array,
however, those skilled in the art will recognize that any of the
examples herein could be modified to produce a sparsely populated
matrix using the grid_register and for_each keywords and
methodologies discussed in detail in the Grid Patent.
[0044] As described in the Grid Patent, a grid is defined as a
monitor that detects a cross product of multiple status
verification events and reports a single status event to a
database. A grid 100, as illustrated in FIG. 4, comprises source
code that includes a monitor declaration 70, one or more axis
declarations 72, zero or more signal declarations 74, zero or more
bus declarations 76, one or more logic expressions 78, and a grid
declaration 80. The monitor declaration 70, signal declaration 74,
bus declaration 76, and logic expressions 78 in a grid 100 are
identical to the monitor declaration 50, signal declaration 52, bus
declaration 54, and logical expressions 58 described above in
connection with FIG. 2 and Table 2. However, as shown in FIG. 4, a
grid 100 also includes one or more axis declarations 72. The axis
declarations are used to produce an array such as that shown in
FIG. 3 wherein each entry comprises the cross product of
interesting verification events. The grid declaration 80 returns
the status event.
[0045] Each individual axis declaration comprises two or more
possible functional states of a functional attribute 84 under test.
FIG. 4 shows several possible functional attributes 84 that might
be suitable as grid axes: op codes 85, cache states 86, bus access
states 87, access sizes 88, and address states 89. Those skilled in
the art will understand that the functional attributes that might
yield interesting grids that are shown and described herein are for
illustration only and are not intended to convey any limitation of
the present invention.
[0046] As shown in FIG. 4, the grid source code 100 is parsed by a
parser 91, which produces a higher-order language computer program
93, which is then compiled by a compiler 95 into object code 97
that runs concurrently with the design simulation as described in
connection with FIG. 1.
[0047] Returning to the grid source code and its constituent
elements, the grid axes are declared in axis declarations 72 that
use the axis keyword and list the enumerated states for all the
cases for that axis. Table 3 below shows the axis declarations for
a grid that monitors and records the states that result from an op
code that is either an add or subtract instruction having 2
operands, wherein each operand is either negative, zero, or
positive. The cross product will be 2 (add/subtract).times.3
(operand1: +, -,0).times.3 (operand2: +, -,0)=18 combinations.
Axis(0) represents the instruction type; Axis(1) represents the
first operand possibilities, and Axis(2) represents the second
operand possibilities.
3 TABLE 3 axis(0) = ADD, SUB; axis(1) = NEG1, ZERO1, POS1; axis(2)
= NEG2, ZERO2, POS2;
[0048] While any number of axes can be specified and in any order,
once the order is determined by the axis declarations, it must be
maintained throughout the grid. In other words, in this grid, once
the first axis, axis(0), is declared to represent the instruction
type, all other attributes of the first grid axis must relate to
the instruction type. Additionally, the number of states for each
axis can be different, but each axis must have at least two
enumerated states. The number of enumerated states in each axis
declaration dictates the size of the axis. In Table 3, the size of
the first axis is 2, the size of the second axis is 3, and the size
of the third axis is 3.
[0049] From the axis declarations, the parser produces higher-order
software code such as C++ code that generates all possible
permutations of the enumerated states along each axis to produce a
matrix of combinations wherein each cell comprises a different
cross-product of one enumerated state along each axis. Note that
while the term "cross-product" suggests that each cell will
comprise a combination of at least two states, one for each of two
axes, the present invention supports one-axis monitors. Therefore,
as used herein, the term "cross-product" includes the case of a
one-axis monitor wherein each cell of the matrix comprises one of
the possible functional states for that axis.
[0050] After the matrix of state combinations is created, the
parser then creates a unique name for each cross-product that is
used to track the instances during a simulation when the design
achieves that cross-product of enumerated states. Consequently,
rather than considering each individual enumerated state on each
axis as a reportable event, the present invention considers each
cross-product of enumerated states to be a single reportable event.
In the embodiment described in the Grid Patent, reportable event
names are formed and reportable events are tracked by taking the
grid base name and concatenating all legal combinations of axis
elements. For example, in a grid named ARITH_INST having the above
axis declarations, the parser would create event names such as
ARITH_INST.ADD_NEG1_NEG2 (corresponding to the cross product of an
add instruction wherein both operands were negative),
ARITH_INST.ADD_NEG1_ZERO2 (corresponding to an add instruction
wherein operand 1 is negative and operand 2 is zero),
ARITH_INST.SUB_NEG1_POS2 (corresponding to a subtract instruction
wherein operand 1 is negative and operand 2 is positive) and so
forth, ultimately creating all 18 possible combinations. In the
Grid Patent, enumerated types are then set up for each axis and
axis variables declared with values that correspond to the possible
functional states specified in the axis declarations. For example,
axis variable declarations that correspond to the Table 3 axis
declarations are shown below in Table 4.
4TABLE 4 axis_0 instr; // axis_0 is an enumerated type with the
values ADD=0, SUB=1 axis_1 operand_type1; // axis_1 is an enum.
type with the values NEG1=0, ZERO1=1, POS1=2 axis_2
operand_type2;
[0051] As described in the Grid Patent and shown in FIG. 4, signal
declarations 74 and bus declarations 76 follow the axis variable
declarations, and are as described above in connection with FIG. 2
and Table 2. Logic expressions 78 follow that test for the
conditions of interest along each axis, and if those conditions are
present, the axis variables are set according to the corresponding
enumerated state for that axis. In the embodiment described in the
Grid Patent, once all axis variables have a legal value, the grid
declaration 80 constructs a string that corresponds to a unique
event name in the database. For example, continuing with the
add/subtract using two operands example from above, the following
grid declaration would be used with the axis declarations and axis
variable declarations shown in Tables 3 and 4 to construct a string
comprising the current values of axis variables instr,
operand_type1, and operand_type2:
grid_return(instr,operand_type1,operand_type2);
[0052] If the instruction is a subtract, operand 1 is negative, and
operand 2 is positive, then grid_return constructs the following
string: SUB_NEG1_POS2, which corresponds to a unique event name in
the database, and a hit is recorded. If a complete list is not
provided to grid_return, then no interesting event was detected
during the simulation cycle.
[0053] One drawback to constructing multiple strings and
maintaining a map that correlates strings to hits is the
computational energy and space required. To improve the grid's
performance and memory requirements, the present invention
identifies each unique reportable event that comprises a cross
product of the possible functional states of different functional
attributes under test via a unique linear index that is an integer,
rather than a string. In this case, the code the parser generates
from grid_return does not construct a string, but instead,
constructs a linear index comprising a group of unique numbers
having a one-to-one correspondence with each unique reportable
event in the grid. In the present invention, grid_return can
maintain a map that correlates each linear index value to the
number of times the grid detected the event represented by the
linear index value, which can later be downloaded directly to a
database and/or converted to the string-based result format
described in the Grid Patent or some other format suitable for
coverage evaluation.
[0054] It is very desirable to keep track of things by indices,
which are both easier to manipulate and have a much smaller memory
footprint than strings. The present invention comprises a grid
wherein each unique reportable event is assigned a unique linear
index, and the overall event hit count for the grid is determined
by creating and maintaining a map that correlates hits to the
linear index. The present invention is capable of detecting,
recording, and reporting hits on a grid having any number of axes,
wherein each axis must have at least two functional states, and can
have any number of functional states.
[0055] The grid source code in the present invention is not
different from the grid source code described in the Grid patent.
In other words, the grid source will include a monitor declaration
70, axis declarations 72, zero or more signal declarations 74, zero
or more bus declarations 76, one or more logic expressions 78, and
a grid declaration 80. As described above, the axis declarations
will use the axis keyword and list two or more possible enumerated
states of a functional attribute 84 under test. The axis variable
declarations will list the axis enumerated type variable name and
set up the possible values for each axis variable. As described
above, the logic expressions will test for the enumerated states
along each axis, and every time a logic expression evaluates true,
the corresponding axis variable is assigned the integer value that
corresponds to the enumerated state within the logic expression.
When all logic expressions evaluate true, a hit is detected, and
grid return returns a list of axis variables that are actually
integers, wherein each integer corresponds to an enumerated state
along an axis.
[0056] The code generated from grid_return then applies a
transformation algorithm that converts the list of integers
returned as axis variables to a single integer that uniquely
identifies the specific cross product of events that has been
detected. The algorithm operates by first creating a numbering
system based upon the grid size, wherein the number of columns or
entries equals the number of axes in the grid n, and the base
number of each column is determined according to the following two
rules:
[0057] Place 0: always a 1's column
[0058] Place p: [size of grid axis (n-p)]*[size of place (p-1)]
[0059] FIG. 5 shows the relative positions of each of the n
columns, with place 0 being the least significant column, and place
n-1 being the most significant column. After the numbering system
is created, the integer values of the axis variables set when the
logic expressions were evaluated are then inserted in the proper
order into the columns of the numbering system. Each column is then
converted to a base 10 integer by multiplying the integer value of
the appropriate axis variable by the base number of its
corresponding column, and the column products are then summed to
create a single linear index.
[0060] To illustrate the operation of the algorithm, assume a grid
having the axis declarations shown below in Table 5, the axis
variable declarations as shown in Table 6, and the following grid
declaration:
[0061] grid_return(instr,operand_type1,operand_type2);
5 TABLE 5 axis(0) = ADD, SUB, MULT, DIV axis(1) = NEG1, ZERO1,
POS1; axis(2) = NEG2, ZERO2, POS2;
[0062]
6TABLE 6 axis_0 instr; // axis_0 is an enumerated type with the
values ADD=0, SUB=1, MULT=2, DIV=3 axis_1 operand_type1; // axis_1
is an enum. type with the values NEG1=0, ZERO1=1, POS1=2 axis_2
operand_type2; // axis_2 is an enum. type with the values NEG2=0,
ZERO2=1, POS2=2
[0063] This is a 3-axis grid having 4.times.3.times.3=36 unique
reportable events. FIG. 6A shows the 3-column conversion numbering
system the present invention creates for this grid. According to
the algorithm, there will be three digits or columns because there
are three axes (n=3). Place 0, the least significant digit, is
always a 1's column. The number base of place 1 is [size of grid
axis (3-1)]*[size of place (1-1)]=[size of grid axis(2)]*[size of
place(0)]=[3]*[1]=3. The number base of place 2 is [size of grid
axis (3-2)]*[size of place (2-1)]=[size of grid axis(1)]*[size of
place(1)]=[3]*[3]=9. So for this grid, the base number of the first
column (leftmost column) is 9, the base number of the second column
(the middle column) is 3, and the least significant column is a 1's
column.
[0064] The conversion of a hit reported as a list of axis variables
that have integer values to a linear index is shown in FIG. 6B,
using as an example a case where the above grid detects a hit where
the operation is a multiply, the first operand is negative, and the
second operand is zero. In that case, the grid would return the
following list of integer variables to grid_return: 2, 0, 1. The
grid_return code first creates the numbering system 98 as described
above, and then inserts the list into the newly-created numbering
system. As shown in FIG. 6B at 92, inserting the axis variables
list into the numbering system places a "2" in the leftmost 9's
column, a "0" in the middle 3's column, and a "1" in the rightmost
1's column. Each column is then converted to base 10 by multiplying
the integer value by its respective base number at 94, and the
three column products are summed at 96 to create the linear index
value--19--that this grid associates with a multiplication
instruction where the first operand is negative and the second
operand is zero.
[0065] Upon closer inspection of FIGS. 6A and 6B and the two rules
listed above, it is evident that another way to describe the
operation of the conversion algorithm is as follows: for any list
of n axis variables associated with an n-axis grid, the unique
linear index is calculated by multiplying the integer value of each
axis variable (except the nth axis variable) by the product of the
sizes of each higher-order axis than the axis to which the axis
variable corresponds, summing the results, and adding the integer
value of the nth axis variable. In this specification, axis B is a
"higher-order axis" than axis A if axis B is declared after axis A
in the grid's axis declaration section. Using the examples from
Tables 3 and 5, axis(1) and axis(2) are higher-order axes than
axis(0). As compared to axis(1), axis(2) is a higher-order axis but
axis(0) is not. Applying the general rule to a 3-axis grid, then,
the integer value of the first axis variable will always be
multiplied by the product of the sizes of axis(1) and axis(2),
because the first axis variable corresponds to axis(0). The integer
value of the second axis variable will always be multiplied by the
size of axis(2), because the second axis variable corresponds to
axis(1) and the only higher-order axis is axis(2). Finally, the
integer value of the third axis variable will always be multiplied
by 1, so its value is simply added to the sum of the column
products.
[0066] Those skilled in the art will recognize that this conversion
methodology requires that the order of the declared axes, their
sizes, and the integer value of their corresponding axis variables
be strictly maintained. Consequently, the n axis declarations are
said to be "ordered," meaning that once the order of the axes is
established by the axis declarations, the order of the axis sizes
and the order of the axis variable lists is also established.
[0067] For completeness, Table 7 shows the linear index that
grid_return would calculate for each reportable event in the above
example grid, and Table 8 shows the full grid monitor code from
which the above example was extracted.
7TABLE 7 Operand_type1/integer Operand_type2/integer Instr/integer
value value value index ADD/0 NEG1/0 NEG2/0 0 ADD/0 NEG1/0 ZERO2/1
1 ADD/0 NEG1/0 POS2/2 2 ADD/0 ZERO1/1 NEG2/0 3 ADD/0 ZERO1/1
ZERO2/1 4 ADD/0 ZERO1/1 POS2/2 5 ADD/0 POS1/2 NEG2/0 6 ADD/0 POS1/2
ZERO2/1 7 ADD/0 POS1/2 POS2/2 8 SUB/1 NEG1/0 NEG2/0 9 SUB/1 NEG1/0
ZERO2/1 10 SUB/1 NEG1/0 POS2/2 11 SUB/1 ZERO1/1 NEG2/0 12 SUB/1
ZERO1/1 ZERO2/1 13 SUB/1 ZERO1/1 POS2/2 14 SUB/1 POS1/2 NEG2/0 15
SUB/1 POS1/2 ZERO2/1 16 SUB/1 POS1/2 POS2/2 17 MULT/2 NEG1/0 NEG2/0
18 MULT/2 NEG1/0 ZERO2/1 19 MULT/2 NEG1/0 POS2/2 20 MULT/2 ZERO1/1
NEG2/0 21 MULT/2 ZERO1/1 ZERO2/1 22 MULT/2 ZERO1/1 POS2/2 23 MULT/2
POS1/2 NEG2/0 24 MULT/2 POS1/2 ZERO2/1 25 MULT/2 POS1/2 POS2/2 26
DIV/3 NEG1/0 NEG2/0 27 DIV/3 NEG1/0 ZERO2/1 28 DIV/3 NEG1/0 POS2/2
29 DIV/3 ZERO1/1 NEG2/0 30 DIV/3 ZERO1/1 ZERO2/1 31 DIV/3 ZERO1/1
POS2/2 32 DIV/3 POS1/2 NEG2/0 33 DIV/3 POS1/2 ZERO2/1 34 DIV/3
POS1/2 POS2/2 35
[0068]
8TABLE 8 // monitor declaration monitor (ARITH_INST) { // set up
the axes axis(0) = ADD, SUB, MULT, DIV; axis(1) = NEG1, ZERO1,
POS1; axis(2) = NEG2, ZERO2, POS2; // declare axis variables of
each enumerated type axis_0 instr; // axis_0 is an enumerated type
with the values ADD=0, SUB=1, // MULT=2, DIV=3 axis_1
operand_type1; // axis_1 is an enum. type with the values NEG1=0,
ZERO1=1, // POS1=2 axis_2 operand_type2; // signal declaration
section bus opcode = "disp_opcode_B[5:0,2]_4h1"; signal *operand1 =
"disp_operand1_type_4h1"; signal *operand2 =
"disp_operand2_type_4h1"; if (bus_val(opcode) == 0) instr = ADD;
else if (bus_val(opcode) == 1) instr = SUB; else if
(bus_val(opcode) == 2) instr = MULT; else if (bus_val(opcode) == 3)
instr = DIV; else return false; // no interesting instructions
being executed, so stop now if (*operand1 == V0) operand_type1 =
NEG1; else if (*operand1 == V1) operand_type1 = ZERO1; else if
(*operand1 == V2) operand_type1 = POS1; else return false; if
(*operand2 == V0) operand_type2 = NEG2; else if (*operand2 == V1)
operand_type2 = ZERO2; else if (*operand2 == V2) operand_type2 =
POS2; else return false; // if the monitor has not exited by this
point, the values for each axis variable // should be set to legal
values, so simply do a grid_return grid_return (instr,
operand_type1, operand_type2); }
MonParse
[0069] In the embodiment described in the Grid Patent, the parser
translates the grid source code, written using the monitor language
and keywords, to generate higher-order language software code that
can then be compiled and executed. The parser of the present
invention, MonParse, does the same thing, but in a slightly
different manner. Whereas the parser in the Grid Patent embodiment
interprets the grid_return keyword to call for a routine that
constructs a string from the returned axis variables that
identifies the reportable event for database logging, the parser of
the present invention now interprets the grid_return keyword to
call for a routine that implements the conversion algorithm
described above and calculates the linear index associated with the
integer variable list returned for each reportable event. In the
present invention, grid_return also maintains a map that indexes
hits at each reportable event to the linear index integer
associated with that reportable event. At the end of the
simulation, the grid can then convert each reportable event that
got a hit during the simulation back into its string, and report
the hit count for each string to the database. Alternatively,
designers may choose to maintain the database in either the linear
index format or in the axis variable list format. Regardless of
which format is chosen, the present invention avoids the need to
generate, maintain, and manipulate strings while the simulation is
running, which frees computing resources and helps the simulation
run more efficiently. In addition, those skilled in the art will
understand that while the parser in this described embodiment
translates the grid source code to C++, which is a standard
higher-order software language, practitioners of the present
invention may chose to parse the grid source code into other
higher-order software languages, or indeed, into any other software
or computer language of their choosing without departing from the
present invention.
[0070] In connection with the parser's new functions described
above, the parser of the described embodiment of the present
invention creates the data structures and routines necessary to
translate the integer version of the axis variable list to its
unique linear index during the simulation, and back to the axis
variable list at the end of the simulation. Likewise, if strings
are to be used, the parser builds the data structures and routines
necessary to translate from the axis variable lists that were hit
during the simulation to their string equivalents for reporting to
the database. Using the 3-axis ARITH_INST grid shown in Table 8 as
an example, the parser of the present invention creates the
following data structures from the ordered axis declarations and
axis variable declarations:
9 [64] // mypCharArray is going to point to these: char
*axis_ARITH_INST_char_0[] = {"add", "subtract", "multiply",
"divide"}; char *axis_ARITH_INST_char_1[] = {"negative", "zero",
"positive"}; char *axis_ARITH_INST_char2[] = {"negative", "zero",
"positive"}; [65] // pArrayEnumChar points to these:
char**mypCharArray ARITH_INST[] = {
(char**)&axis_ARITH_INST_char- _0,
(char**)&axis_ARITH_INST_char_1,
(char**)&axis_ARITH_INST_char_2 }; [66] // pDims points to this
array int mypDims ARITH_INST[] = { 4, // pDims[0] 3, // pDims[1] 3
// pDims[2] };
[0071] As described above, in the present invention, MonParse
interprets the grid_return keyword to call for a function that
converts the integer list that specifies a hit in a grid cell to a
single linear index that is an integer that uniquely identifies the
specific cross product of events that has been detected. Table 9
below shows a typical C++ routine that MonParse might generate to
convert the integer list to the linear index, in accordance to the
algorithm described above. MonParse also creates a routine that
uses the data structures described above, the number of dimensions
in the grid, the base name of the grid, and the linear index to
recreate the name of each grid point that was hit. Table 10 below
shows a typical C++ routine that MonParse might generate to convert
the linear index to the concatenated strings disclosed in the Grid
Patent for reporting to the database.
10TABLE 9 // generated code related to the grid_return: // note how
the final index is calculated - each grid creates its own number
system from the number of grid axes and the size of certain axes,
and the linear index is calculated using the number system and the
variables a (integer value for axis variable instr), b (integer
value for axis variable operand_type1), and c (integer value for
axis variable operand_type 2). This code creates the linear index
for the n-dimensional grid. void grid Return(int a,int b,int c) {
IGrid Index = c; int IRemainingProduct = 1; IRemainingProduct *=
pDims[2]; IGridIndex = IGridIndex + (b * IRemainingProduct);
IRemainingProduct *= pDims[1]; IGridIndex = IGridIndex + (a *
IRemainingProduct); }
[0072]
11TABLE 10 // This code works irrespective of the number of
dimensions and the // size of each dimension. This code takes a
linear index into the // n-dimensional grid and converts it to the
string it represents. The // string is returned in szMonName, the
first argument. IIndex is the // linear index, INumDims is the
number of dimensions in the grid. // pArrayEnumChar is the pointer
to the array of strings that comprise the // definition of the
grid, pDims is a pointer to an array of integers which // define
the size of each dimension, and szMonBaseName is the base // name
of the monitor (common to all grid points represented by the //
monitor)
//------------------------------------------------------------------------
--------------- void ConstructMonName(char *szMonName, int IIndex,
int INumDims, char ***pArrayEnumChar, int *pDims, char
*szMonBaseName) { int *incArray = new int[INumDims]; // we create
our own number system here . . . incArray[INumDims - 1] = 1; if
(INumDims > 1) { int IMultiplier = 1; for (int i = INumDims - 2;
i >= 0; i--) { IMultiplier *= pDims[i+1]; incArray[i] =
IMultiplier; } } int IAmountLeft = IIndex; int IIncAnswer;
sprintf(szMonName,"%s.",szMonBaseName); for (int j = 0; j <
INumDims; j++) { // separate axes with underscore if (j)
strcat(szMonName,"_"); // look at our number system to determine if
we have any of this index if (IAmountLeft >= incArray[j]) {
IIncAnswer = IAmountLeft / incArray[j]; IAmountLeft -= IIncAnswer *
incArray[j]; } else IIncAnswer = 0; strcat(szMonName,
pArrayEnumChar[j][IIncAnswer]); }
[0073] To summarize, the present invention comprises a method and
apparatus that monitors the simulation of a digital design such as
a processor, and detects and reports certain events and
combinations of events to a database. The grid includes a monitor
declaration that provides a unique name for the grid, n ordered
axis declarations wherein n is at least 1 that name a first through
a nth axis, one or more logic expressions, and a grid declaration.
Each axis declaration corresponds to a functional attribute of the
design and lists two or more functional states of the functional
attribute. The size of each axis comprises the number of functional
states listed in the axis declaration. The logic expressions
evaluate whether the design has achieved one of the functional
states along each axis, and if a logic expression relating to an
axis evaluates true, it sets the axis variable for that axis to the
integer value corresponding to the functional state found. If
values are set for all axis variables, the grid declaration
converts the n axis variables to a unique linear index value that
corresponds to the cross-product of the functional states achieved
by the design, and records hits at each unique linear index value
determined. The grid declaration can maintain a hit map indexed to
the unique linear index for later downloading to a database.
[0074] The grid calculates the unique linear index value by
multiplying the integer value of each axis variable (except the nth
axis variable) by the product of the sizes of each higher-order
axis than the axis to which said axis variable corresponds, summing
the results, and adding the integer value of the nth said axis
variable.
[0075] The present invention also includes a parser that translates
the grid source code into a computer program that may comprise a
standard higher-order software language such as C++ or any other
software or computer language desired by the user. In some
embodiments, the parser further translates each unique linear index
value to a character string comprising a concatenation of character
strings that correlate to the grid name and to each functional
state within the cross-product of functional states achieved by the
design. The hit map can be reported to the database in either the
linear index format or the character string format. The present
invention further comprises embodiments where a grid uses either a
fully populated state array, wherein all permutations of valid
states for each axis are included, or a sparsely populated state
array, wherein only permutations of the valid states of each axis
that are of interest to the designer are included.
[0076] Other embodiments of the invention will be apparent to those
skilled in the art after considering this specification or
practicing the disclosed invention. The specification and examples
above are exemplary only, with the true scope of the invention
being indicated by the following claims.
* * * * *